Sugarcane streak mosaic virus P1 protein targets the BES1 transcription factor to subvert DAMP-triggered immunity in plant

Sugarcane streak mosaic virus (SCSMV) is the major cause of sugarcane mosaic disease. Its P1 protein (P1^SCSMV) is crucial for pathogenesis, but how it disrupts plant immunity remains unclear. Here, we found that P1^SCSMV directly binds to the core transcription factor of brassinosteroid signaling, NbBES1, disrupting its binding to the E-box elements of the xyloglucan endotransglucosylase/hydrolase gene 1 (<i>NbXTH1</i>) promoter and suppressing <i>NbXTH1</i> transcription. <i>NbXTH1</i> overexpression enhanced the plant resistance to fungal/viral infection, improved the contents of xyloglucan, which directly induced a damage-associated molecular pattern triggering innate immunity (DTI) and expression of several defense genes, and accompanied with a thickened middle lamellae and primary cell wall. Reduced xyloglucan due to <i>NbXTH1</i> downexpression further weakened DTI responses and a thinner cell wall. This study reveals how a viral protein subverts cell wall-mediated immunity and identifies NbXTH1 as a broad-spectrum disease resistance factor. Our findings support using xyloglucan or NbXTH1 to engineer broad-spectrum disease resistance in crops.